LINEAR TECHNOLOGY LTC3208 Technical data

FEATURES

LTC3208

High Current Software

Confi gurable Multidisplay

LED Controller

U

DESCRIPTIO

■

1x/1.5x/2x Charge Pump Provides Up to 95%

Effi ciency

■

Up to 1A Total Output Current

■

17 Current Sources Available as MAIN, SUB, RGB,

CAM and AUX LED Drivers

■

LED ON/OFF, Brightness Level and Display

Confi guration Programmable Using 2-Wire I

2

C™

Interface

■

Low Noise Constant Frequency Operation with Flying

Capacitor Edge Rate Control

■

Automatic Charge Pump Mode Switching

■

Internal Soft-Start Limits Inrush Current During

Startup and Mode Switching

■

Open/Shorted LED Protection

■

Short-Circuit/Thermal Protection

■

256 Brightness States for MAIN and SUB Displays

■

4096 Color Combinations for the RGB Display

■

5mm × 5mm 32-Lead QFN Plastic Package

U

APPLICATIO S

■

Video/Camera Phones with QVGA + Displays

, LTC and LT are registered trademarks of Linear Technology Corporation. All other

trademarks are the property of their respective owners. Protected by U.S. Patents including

6411531.

The LTC®3208 is a highly integrated multidisplay LED
controller. The part contains a 1A high effi ciency, low noise
charge pump to provide power to the MAIN, SUB, RGB, CAM
and AUX LED displays. The LTC3208 requires only small
ceramic capacitors and one current set resistor to form a
complete LED power supply and current controller.

The maximum display currents are set by a single ex­ternal resistor. Current for each LED is controlled by a
precision internal current source. Dimming and On/Off

2

for all displays is achieved via the I

C serial interface.
256 brightness levels are available for the MAIN and SUB
displays. 16 levels are available for the RGB and CAM
displays. Four AUX current sources can be independently

2

assigned via the I

C port to the CAM, SUB, MAIN or AUX

DAC controlled displays.

The LTC3208 charge pump optimizes effi ciency based
on the voltage across the LED current sources. The part
powers up in 1x mode and will automatically switch to
boost mode whenever any enabled LED current source
begins to enter dropout. The fi rst dropout switches the
part into 1.5x mode and a subsequent dropout switches
the LTC3208 into 2x mode. The part is available in a small
5mm × 5mm 32-lead QFN package.

TYPICAL APPLICATIO

C3

C2

2.2mF

2.2mF

C1P C1M C2P C2M

V

BAT

C1

4.7mF

ENABLE DISABLE

LOW HI

V

BAT1,2,3

SCL/SDA

I2C

ENRGBS

CAMHL

R

REF

24.3k
1%

LTC3208

CPO

MAIN1-4

SUB1-2

CAM1-4

RGB

AUX1-4

GND

C4

4.7mF

4

2

4

3

4

U

MAIN SUB CAMERA RGB AUX

3208 TA01a

4-LED MAIN Display

Effi ciency vs Input Voltage

100

90

80

) (%)

70

IN

/P

60

LED

50

40

30

EFFICIENCY (P

20

4 LEDs AT 15mA/LED

AT 15mA = 3.2V)

(TYP V

F

10

= 25°C

T

A

0

3.2

3.0

3.6

3.4

3.8

V

(V)

BAT

4.0

4.44.2

3208 TA01b

3208fa

1

LTC3208

WW

W

U

ABSOLUTE AXI U RATI GS

(Note 1)

V

, DVCC, CPO to GND ................................– 0.3 to 6V

BAT

SDA, SCL, ENRGBS, CAMHL .....– 0.3V to (DV

(Note 2) ............................................................1.3A

I

CPO

I

MAIN1-4

, I

I

RED

I

CAM1-4

CPO, R

, I

GRN

, I

REF

AUX1-4

(Note 3) .......................................33mA

SUB1-2

, I

(Note 3) .......................................33mA

BLUE

(Note 3) ......................................120mA

Short-Circuit Duration .................... Indefi nite

Operating Temperature Range (Note 4) .. – 40°C to 85°C

Storage Temperature Range .................. – 65°C to 125°C

+ 0.3V)

CC

UUW

PACKAGE/ORDER I FOR ATIO

TOP VIEW

BAT1

CPO

C1P

V

C2P

ENRGBS

C1M

C2M

32 31 30 29 28 27 26 25

1CAM1

CAM2

2

CAM3

3

CAM4

4

AUX1

5

AUX2

6

AUX3

7

AUX4

8

9 10 11 12

CAMHL

32-LEAD (5mm × 5mm) QFN

EXPOSED PAD IS GND (PIN 33)

MUST BE SOLDERED TO PCB

T

JMAX

33

13 14 15 16

SDA

BAT3

R

V

UH PACKAGE

REF

SCL

= 125°C, θJA = 34°C/W

ORDER PART NUMBER UH PART MARKING

LTC3208EUH 3208

Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/

Consult LTC Marketing for parts specifi ed with wider operating temperature ranges.

GND

V

24

BAT2

RED

23

GRN

22

BLUE

21

SUB1

20

SUB2

19

MAIN4

18

MAIN3

17

VCC

D

MAIN1

MAIN2

●

The

ELECTRICAL CHARACTERISTICS

temperature range, otherwise specifi cations are at T

= 25°C. V

A

denotes the specifi cations which apply over the full operating

= 3.6V, DVCC = 3V, ENRGBS = Hi, R

BAT

= 24k, C2 = C3 = 2.2µF,

REF

C1 = C4 = 4.7µF, unless otherwise noted.

PARAMETERS CONDITIONS MIN TYP MAX UNITS

V

Operating Voltage

BAT

Operating Current I

I

VBAT

I
I

Operating Voltage

DV

CC

Operating Current DVCC = 1.8V, Serial Port Idle

DV

CC

UVLO Threshold 1.5 V

V

BAT

UVLO Threshold 1 V

DV

CC

Shutdown Current DVCC = 1.8V 3.2 µA

V

BAT

R

REF

VR

REF

RR

Reference Resistor Range

REF

= 0, 1x Mode, LEDs Disabled 280 µA

CPO

= 0, 1.5x Mode 4.7 mA

CPO

= 0, 2x Mode 7 mA

CPO

White LED Current (MAIN1-4, SUB1-2), 8-Bit Linear DACs

Full-Scale LED Current MAIN, SUB = 1V
Minimum (1LSB) LED Current MAIN, SUB = 1V 108 µA
LED Current Matching Any Two MAIN or SUB Outputs, 50% FS 1 %

LED Dropout Voltage I

= FS 180 mV

LED

●

2.9 4.5 V

●

1.5 5.5 V

●

1 µA

●

1.195 1.215 1.235 V

●

22 30 k

●

25.3 27.5 29.7 mA

3208fa

2

LTC3208

ELECTRICAL CHARACTERISTICS

The
temperature range, otherwise specifi cations are at T

= 25°C. V

A

C1 = C4 = 4.7µF, unless otherwise noted.

PARAMETERS CONDITIONS MIN TYP MAX UNITS
White LED Current (CAM1-4), 4-Bit Linear DAC

Full-Scale LED Current CAM = 1V
Minimum (1LSB) LED Current CAM = 1V 6.96 mA
LED Current Matching Any Two CAM Outputs, 50% FS 1 %
LED Dropout Voltage I

White LED Current (AUX1-4, AUX Outputs Assigned to AUX DAC), 4-Bit Linear DAC

Full-Scale LED Current AUX = 1V
Minimum (1LSB) LED Current AUX = 1V 1.73 mA

LED Current Matching Two AUX Outputs, 50% FS 1 %

LED Dropout Voltage I

Full-Scale AUX LED Current AUX Connected to CAM DAC, AUX = 1V 104.9 mA
Full-Scale AUX LED Current AUX Connected to SUB or MAIN DAC, AUX = 1V 28.1 mA

RGB LED Current (RED, GREEN, BLUE), 4-Bit Exponential DAC

DAC Code 0001 RED, GREEN, BLUE = 1V 0.24 mA
DAC Code 0010 RED, GREEN, BLUE = 1V 0.32 mA
DAC Code 0011 RED, GREEN, BLUE = 1V 0.46 mA
DAC Code 0100 RED, GREEN, BLUE = 1V 0.63 mA
DAC Code 0101 RED, GREEN, BLUE = 1V 0.89 mA
DAC Code 0110 RED, GREEN, BLUE = 1V 1.22 mA
DAC Code 0111 RED, GREEN, BLUE = 1V 1.74 mA
DAC Code 1000 RED, GREEN, BLUE = 1V 2.42 mA
DAC Code 1001 RED, GREEN, BLUE = 1V 3.47 mA
DAC Code 1010 RED, GREEN, BLUE = 1V 4.73 mA
DAC Code 1011 RED, GREEN, BLUE = 1V 6.7 mA
DAC Code 1100 RED, GREEN, BLUE = 1V 9.47 mA
DAC Code 1101 RED, GREEN, BLUE = 1V 13.56 mA
DAC Code 1110 RED, GREEN, BLUE = 1V 19.05 mA
DAC Code 1111 RED, GREEN, BLUE = 1V 27.06 mA
Charge Pump (CPO)
1x Mode Output Impedance 0.35

1.5x Mode Output Impedance V
2x Mode Output Impedance V
CPO Voltage Regulation 1.5x Mode, I

2x Mode, I
CLOCK Frequency

SDA, SCL, ENRGBS, CAMHL

V

, (Low Level Input Voltage)

IL

V

, (High Level Input Voltage)

IH

V

, Digital Output Low (SDA) I

OL

I

SDA, SCL, ENRGBS, CAMHL = DVCC

IH

I

SDA, SCL, ENRGBS, CAMHL = 0V

IL

Serial Port Timing (Notes 6, 7)

t

Clock Operating Frequency 400 kHz

SCL

t

Bus Free Time Between Stop and Start Condition 1.3 µs

BUF

t

Hold Time After (Repeated) Start Condition 0.6 µs

HD,STA

= FS 540 mV

LED

= FS 140 mV

LED

= 3V, V

BAT

BAT

PULLUP

= 3V, V

= 3mA

CPO

CPO

CPO

CPO

●

denotes the specifi cations which apply over the full operating

= 3.6V, DVCC = 3V, ENRGBS = Hi, R

BAT

●

92.5 102.5 112.5 mA

●

23 26 28.5 mA

= 4.2V (Note 5) 2
= 4.8V (Note 5) 2.2
= 2mA 4.53 V

= 2mA 5.02 V

●

0.6 0.9 1.2 MHz

●

●

●

●

–1 1 µA

●

–1 1 µA

= 24k, C2 = C3 = 2.2µF,

REF

0.3 • DVCC V

0.7 • DVCC V

0.18 0.4 V

3208fa

3

LTC3208

The

ELECTRICAL CHARACTERISTICS

temperature range, otherwise specifi cations are at T

= 25°C. V

A

●

denotes the specifi cations which apply over the full operating

= 3.6V, DVCC = 3V, ENRGBS = Hi, R

BAT

= 24k, C2 = C3 = 2.2µF,

REF

C1 = C4 = 4.7µF, unless otherwise noted.

PARAMETERS CONDITIONS MIN TYP MAX UNITS

Repeated Start Condition Setup Time 0.6 µs

t

SU,STA

t

Stop Condition Setup Time 0.6 µs

SU,STO

t

HD,DAT(OUT)

t

HD,DAT(IN)

t

SU,DAT

t

LOW

t

HIGH

t

Clock Data Fall Time 20 300 ns

f

t

Clock Data Rise Time 20 300 ns

r

t

SP

Note 1: Absolute Maximum Ratings are those values beyond which the
MTBF of a device may be impaired.

Note 2: Based on long-term current density limitations. Assumes an
operating duty cycle of ≤10% under absolute maximum conditions for
durations less than 10 seconds. Max charge pump current for continuous
operation is 500mA.

Note 3: Based on long-term current density limitations.

Data Hold Time 0 900 ns

Input Data Hold Time 0 ns

Data Setup Time 100 ns

Clock Low Period 1.3 µs

Clock High Period 0.6 µs

Spike Suppression Time 50 ns

Note 4: The LTC3208E is guaranteed to meet performance specifi cations
from 0°C to 70°C. Specifi cations over the –40°C to 85°C ambient
operating temperature range are assured by design, characterization and
correlation with statistical process controls.

Note 5: 1.5x mode output impedance is defi ned as (1.5V
2x mode output impedance is defi ned as (2V

Note 6: All values are referenced to V

IH

– V

BAT

and VIL levels.

CPO

)/I

BAT

OUT

– V

.

CPO

)/I

OUT

Note 7: Guaranteed by Design.

.

UW

TYPICAL PERFOR A CE CHARACTERISTICS

Mode Switch Dropout Times 1.5x Mode CPO Ripple 2x Mode CPO Ripple

V

CPO

1V/DIV

5V

TA = 25°C

= 3.6V

V

BAT

1x

1.5x

250µs/DIV

2x

20mV/DIV

AC COUPLED

3208 G01

TA = 25°C

= 3.6V

V

BAT

= 400mA

I

CPO

= 4.7µF

C

CPO

V

CPO

500ns/DIV

3208 G02

V

CPO

20mV/DIV

AC COUPLED

TA = 25°C

= 3.6V

V

BAT

= 400mA

I

CPO

= 4.7µF

C

CPO

500ns/DIV

3208 G03

4

3208fa

UW

TYPICAL PERFOR A CE CHARACTERISTICS

LED Pin Dropout Voltage
vs LED Pin Current

600

V

= 3.6V

BAT

= 25°C

T

A

500

400

300

200

100

LED PIN DROPOUT VOLTAGE (mV)

1x Mode Switch Resistance vs
Temperature

0.45
I

= 200mA

CPO

0.40

V

= 3.6V

BAT

0.35

0.30

SWITCH RESISTANCE (Ω)

V

V

BAT

BAT

= 3.3V

= 3.9V

LTC3208

1.5x Mode Charge Pump Open-Loop
Output Resistance vs Temperature

– V

2.5

2.3

2.1

1.9

SWITCH RESISTANCE (Ω)

1.7

(1.5V

BAT

V

= 3V

BAT

= 4.2V

V

CPO

C2 = C3 = 2.2µF
C4 = 4.7µF

CPO

)/I

CPO

0

10

20 40 50 10090

30 60 70 80

LED CURRENT (mA)

1.5x Mode CPO Voltage
vs Load Current

4.8

4.6

4.4

4.2
V

= 3V

BAT

4.0

CPO VOLTAGE (V)

C2 = C3 = 2.2µF

3.8

C4 = 4.7µF

= 25°C

T

A

3.6

100 200 300 400

LOAD CURRENT (mA)

Oscillator Frequency
vs Supply Voltage

940

930

920

910

900

890

880

FREQUENCY (kHz)

870

860

850

840

2.7

TA = 25°C

3.3 3.6 3.9

3.0
V

SUPPLY VOLTAGE (V)

BAT

3.2V

3.1V

TA = –40°C

3.4V

3.3V

TA = 85°C

3208 G04

3.6V

3.5V

3208 G07

4.2 4.5

3208 G10

0.25
–15 10 35 85

–40

TEMPERATURE (°C)

60

3208 G05

1.5
–15 10 35 85

–40

TEMPERATURE (°C)

60

3208 G06

2x Mode Charge Pump Open­Loop Output Resistance vs

– V

Temperature (2V

2.8
V

= 3V

BAT

= 4.8V

V

CPO

C2 = C3 = 2.2µF

2.6
C4 = 4.7µF

2.4

2.2

2.0

SWITCH RESISTANCE (Ω)

1.8

SHUTDOWN CURRENT (µA)

DV

1.6

0.4

0.3

0.2

0.1

CC

5000

–15 10 35 85

–40

Shutdown Current

DV

CC

vs DV

0

2.7

Voltage

CC

V

= 3.6V

BAT

3.0

BAT

TEMPERATURE (°C)

TA = 85°C

3.3 3.6 3.9
DVCC VOLTAGE (V)

CPO

TA = –40°C

TA = 25°C

)/I

CPO

60

3208 G08

4.2 4.5

3208 G11

2x Mode CPO Voltage
vs Load Current

5.2

5.1

5.0

4.9

4.8

4.7

4.6

CPO VOLTAGE (V)

4.5

4.4

4.3

4.2

8.5

7.5

6.5

5.5

4.5

3.5

SHUTDOWN CURRENT (µA)

BAT

V

2.5

1.5

V

= 3V

BAT

= 3.1V

V

BAT

= 3.2V

V

BAT

= 3.3V

V

BAT

= 3.4V

V

BAT

= 3.5V

V

BAT

= 3.6V

V

BAT

C2 = C3 = 2.2µF
C4 = 4.7µF

= 25°C

T

A

100 200 300 600 700

LOAD CURRENT (mA)

V

Shutdown Current

BAT

Voltage

vs V

BAT

D

= 3V

VCC

TA = 25°C

3.0

3.3 3.6 3.9
V

2.7

TA = 85°C

TA = –40°C

VOLTAGE (V)

BAT

800400 5000

3208 G09

4.2 4.5

3208 G12

3208fa

5

LTC3208

UW

TYPICAL PERFOR A CE CHARACTERISTICS

1x Mode No Load V

Voltage

V

BAT

300

TA = 25°C

290

280

270

260

250

CURRENT (µA)

240

BAT

V

230

220

210

200

2.7

3.3 3.6 3.9

3.0
V

CAM Pin Current vs
CAM Pin Voltage

120

V

= 3.6V

BAT

= 25°C

T

A

100

80

60

40

CAM PIN CURRENT (mA)

20

0

0

0.2 0.4 0.6 0.8
CAM PIN VOLTAGE (V)

VOLTAGE (V)

BAT

Current vs

BAT

4.2 4.5

3208 G13

3208 G16

1.0

1.5x Mode Supply Current
vs I

(IV

CPO

40

VIN = 3.6V

= 25°C

T

A

30

20

SUPPLY CURRENT (mA)

10

0

0

– 1.5I

BAT

200 400 600

LOAD CURRENT (mA)

CPO

RGB LED Current vs Input Code

30

V

= 3.6V

BAT

= 25°C

T

A

= 24.3k

R

25

REF

20

15

10

RGB LED CURRENT (mA)

5

0

2468

HEX CODE

2x Mode Supply Current

)

800

3208 G14

vs I

(IV

CPO

25

VIN = 3.6V

= 25°C

T

A

20

15

10

SUPPLY CURRENT (mA)

5

0

0 200 400 600 800100 300 500 700

– 2I

BAT

CPO

LOAD CURRENT (mA)

)

3208 G15

CAM LED Current vs
Input Code

110

V

= 3.6V

BAT

100

= 25°C

T

A

= 24.3k

R

REF

90

80

70

60

50

40

30

CAM LED CURRENT (mA)

20

10

0

3208 G17

FEDCBA10 3579

2468

HEX CODE

FEDCBA10 3579

3208 G18

AUX LED Current vs Input Code

28

V

= 3.6V

BAT

26

= 25°C

T

A

24

= 24.3k

R

REF

22
20
18
16
14
12
10

8

AUX LED CURRENT (mA)

6
4
2
0

2468

HEX CODE

6

FEDCBA103579

3208 G21

Main/Sub LED Current vs
Input Code Main/Sub INL

28

V

= 3.6V

BAT

26

= 25°C

T

A

24

= 24.3k

R

REF

22
20
18
16
14
12
10

8
6

MAIN/SUB LED CURRENT (mA)

4
2
0

20 40 60 80

HEX CODE

FFF0E0D0C0B0A0100 30507090

3208 G19

1.0

0.8

0.6

0.4

0.2

0

–0.2

–0.4

MAIN/SUB INL (LSB)

–0.6

–0.8

–1.0

80

HEX CODE

FF1

3208 G20

3208fa

UUU

PI FU CTIO S

LTC3208

CAM1-4 (Pins 1, 2, 3, 4): Current Source Outputs for
the CAM Display White LEDs. The LEDs on the CAM
display can be set from 0mA to 102mA in 16 steps via
software control and internal 4-bit linear DAC. Two 4-bit
registers are available. One is used to program the high
camera current and the second the low camera current.
These registers can be selected via the serial port or the
CAMHL pin. Each output can be disabled by connecting
the output to CPO. Setting data in REGF to 0 disables all
CAM outputs. (See Applications Information.)

AUX1-4 (Pins 5, 6, 7, 8): Current Source Outputs for the
AUX Display White LEDs. When used as a separate display,
the LED current sources of the AUX display can be set
from 0mA to 26mA in 16 steps via software control and
internal 4-bit linear DAC. In addition, these outputs can
be connected individually as needed to the CAM, SUB or
MAIN displays and driven from each display’s associated
DAC. AUX 1, 2 and 3 can be disabled by connecting the
output to CPO. AUX 4 can be used as an open drain I
controlled logic output but cannot be disabled by con­necting to CPO when confi gured as logic output. Setting
data in REGE and REGB2 to 0 disables all AUX outputs.
(See Applications Information.)

CAMHL (Pin 9): Logic Input. Selects CAM high register
when asserted High and CAM Low Register when low.
The high to low transition automatically resets the charge
pump mode to 1x.

SCL (Pin 10): I2C Clock Input. The logic level for SCL is

referenced to DVCC.

SDA (Pin 11): I2C Data Input for the Serial Port. Serial
data is shifted in one bit per clock to control the LTC3208.
The logic level is referenced to DV

CC

.

2

C

V

BAT3, 2, 1

Device. Three separate pins are used to isolate the charge
pump from the analog sections to reduce noise. All pins
must be connected together externally and bypassed with
a 4.7µF low ESR ceramic capacitor. The 4.7µF bypass
capacitor should be connected close to V
capacitor should be connected close to V

R

REF

Current for all Displays. The R
external resistor to ground sets the reference currents for
all display DACs and support circuits. Since this resistor
biases all circuits within the LTC3208, the value is limited
to a range of 22k to 30k.

DVCC (Pin 14): Supply Voltage for all Digital I/O Lines.
This pin sets the logic reference level of the LTC3208.
A UVLO circuit on the DVCC pin forces all registers to all
0s whenever DVCC is below the DVCC UVLO threshold.
Bypass to GND with a 0.1µF capacitor.

MAIN1-4 (Pins 15,16,17,18): Current Source Outputs
for the MAIN Display White LEDs. The LEDs on the MAIN
display can be set from 0µA to 27.5mA in 256 steps via
software control and internal 8-bit linear DAC. Each output
can be disabled externally by connecting the output to CPO.
Setting data in REGC to 0 disables all MAIN outputs.

SUB2, SUB1 (Pins 19, 20): Current Source Outputs for
the SUB Display White LEDs. The LEDs on the SUB display

can be set from 0µA to 27.5mA in 256 steps via software
control and an internal 8-bit linear DAC. Each output can
be disabled externally by connecting the output to CPO.
Setting the data in REGD to 0 disables all SUB outputs.

(Pins 12, 24, 30): Supply Voltage for the Entire

. A 0.1µF

BAT2

.

BAT3

(Pin 13): Controls the Maximum Amount of LED

voltage is 1.215V. An

REF

3208fa

7

LTC3208

UUU

PI FU CTIO S

BLUE, GRN, RED (Pins 21, 22, 23): Current Source
Outputs for the RGB Illuminator LEDs. The RGB currents
can be independently set via the serial port. Currents
up to 27mA can be programmed over 16 steps via the
three internal 4-bit exponential DACs. These outputs can
also be used as open drain I
When confi gured this way, these outputs cannot be ex­ternally disabled by connecting to CPO. Setting data to
0 in REGA1 disables RED, REGA2 disables GREEN and
REGB1 disables BLUE.

GND (Pins 25, 33): System Ground. Connect Pin 25 and
exposed pad Pin 33 directly to a low impedance ground
plane.

C2M, C1M, C2P, C1P (Pins 26, 27, 29, 31): Charge
Pump Flying Capacitor Pins. 2.2µF X7R or X5R ceramic

2

C controlled logic outputs.

capacitors should be connected from C1P to C1M and
C2P to C2M.

ENRGBS (Pin 28): Logic Input. This pin is normally high
and is used to enable or disable the RED, GREEN and
BLUE LEDs or the SUB LEDs. The selection between RGB
or SUB is made via an internal programmable bit. When
the pin is toggled from low (disable) to high (enable), the
LTC3208 illuminates either the RGB display with a color
combination that was previously programmed, or the SUB
display at its previously programmed current. The logic
level is referenced to DV

CPO (Pin 32): Output of the Charge Pump Used to Power
All LEDs. A 4.7µF X5R or X7R ceramic capacitor should
be connected to ground.

CC

.

8

3208fa